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Vibrational spectroscopy of individual surface adsorbates

各个表面吸附物的振动光谱

基本信息

批准号：
17340089
负责人：
UEHARA Yoichi
金额：
$ 10.64万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17340089/
关键词：
Vibrational spectroscopy identification of atoms and molecules atomic spatial resolution STM tunneling phenomena 原子・分子光学分光

项目摘要

The purpose of the present research was to develop the method that makes it possible to determine the vibrational energies of individual species adsorbed on solid surfaces. For this purpose, we investigated scanning tunneling microscope (STM)light emission spectra of adsorbates. We have found that vibrational motions of the adsorbate being located beneath the tip are excited through two channels in the STM light emission process. One is the direct excitation by the tunneling current and the other is that by localized surface plasmons (LSP) being excited by the tunneling currant. When the Former channel is dominant, periodic fine structures are seen in the STM light emission spectra. Since the period of tine fine structures agrees with the vibrational energy of the absorbate, one can determine its value through the Fourier analysis of the STM light emission spectra. When the latter channel (i.e, excitation by LSP) is dominant; stepwise structures appear at the vibrational energies below … More the quantum cutoff in the STM light emission spectra. The value of the quantum cutoff is determined by the measurement condition. Hence, one can also know the vibrational elegies from the latter channel.. Theoretical investigations show that the periodic fine structures are reproducible in the framework of the currant fluctuation theory of STM light emission. The stepwise structures can be understood as a kind of Raman scattering of LSP by the adsorbate. The vibrational modes that can be determined by the present method were also explored, those of hydrogen atoms, oxygen atoms, and single molecules of benzene adsorbed on various lands of substrates including Ni, Cu, and Ag were deduced from the STM light emission spectra. Furthermore, we succeed in determining the phonon energies of substrate itself from the STM light emission spectra. This result shows that the present method is applicable to vibrational spectroscopy of not only adsorbates but also solid materials (e g., nano-materials). Less

本研究的目的是发展的方法，使之有可能确定吸附在固体表面上的单个物种的振动能。为此，我们研究了吸附物的扫描隧道显微镜（STM）光发射光谱。我们发现，在STM发光过程中，位于针尖下方的吸附质的振动运动是通过两个通道激发的。一种是由隧穿电流直接激发，另一种是由隧穿电流激发的局域表面等离子体激元（LSP）。当Former通道占主导地位时，在STM光发射光谱中看到周期性的精细结构。由于精细结构的周期与晶体的振动能一致，因此可以通过STM光发射谱的傅里叶分析来确定其值。当后一个通道（即LSP激发）占主导地位时，在以下振动能量处出现阶梯结构： ...更多信息 STM光发射光谱中的量子截止。量子截止的值由测量条件决定。因此，人们也可以从后一个渠道知道振动挽歌。理论研究表明，在STM光发射电流涨落理论的框架下，周期性精细结构是可再现的。这种阶梯状结构可以理解为吸附质对LSP的一种拉曼散射。本文还探讨了用本方法可以确定的振动模式，从STM光发射光谱中推导出吸附在各种衬底（包括Ni、Cu和Ag）上的氢原子、氧原子和苯单分子的振动模式。此外，我们还成功地从STM光发射谱中确定了衬底本身的声子能量。这一结果表明，本方法不仅适用于吸附物的振动光谱，而且适用于固体材料（例如，纳米材料）。少